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In
computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, ...
, a namespace is a set of signs (''names'') that are used to identify and refer to objects of various kinds. A namespace ensures that all of a given set of objects have unique names so that they can be easily identified. Namespaces are commonly structured as hierarchies to allow reuse of names in different contexts. As an analogy, consider a system of naming of people where each person has a given name, as well as a family name shared with their relatives. If the first names of family members are unique only within each family, then each person can be uniquely identified by the combination of first name and family name; there is only one Jane Doe, though there may be many Janes. Within the namespace of the Doe family, just "Jane" suffices to unambiguously designate this person, while within the "global" namespace of all people, the full name must be used. Prominent examples for namespaces include file systems, which assign names to files. Some
programming language A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language. The description of a programming ...
s organize their variables and subroutines in namespaces.
Computer network A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ...
s and
distributed system A distributed system is a system whose components are located on different networked computers, which communicate and coordinate their actions by passing messages to one another from any system. Distributed computing is a field of computer sci ...
s assign names to resources, such as computers, printers,
website A website (also written as a web site) is a collection of web pages and related content that is identified by a common domain name and published on at least one web server. Examples of notable websites are Google, Facebook, Amazon, and Wi ...
s, and remote files.
Operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also i ...
s can partition kernel resources by isolated namespaces to support virtualization
containers A container is any receptacle or enclosure for holding a product used in storage, packaging, and transportation, including shipping. Things kept inside of a container are protected on several sides by being inside of its structure. The term ...
. Similarly, hierarchical file systems organize files in directories. Each directory is a separate namespace, so that the directories "letters" and "invoices" may both contain a file "to_jane". In
computer programming Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as anal ...
, namespaces are typically employed for the purpose of grouping symbols and identifiers around a particular functionality and to avoid
name collision In computer programming, a name collision is the nomenclature problem that occurs when the same variable name is used for different things in two separate areas that are joined, merged, or otherwise go from occupying separate namespaces to shari ...
s between multiple identifiers that share the same name. In networking, the
Domain Name System The Domain Name System (DNS) is a hierarchical and distributed naming system for computers, services, and other resources in the Internet or other Internet Protocol (IP) networks. It associates various information with domain names assigned t ...
organizes websites (and other resources) into
hierarchical namespace In computing, a namespace is a set of signs (''names'') that are used to identify and refer to objects of various kinds. A namespace ensures that all of a given set of objects have unique names so that they can be easily identified. Namespaces ...
s.


Name conflicts

Element names are defined by the developer. This often results in a conflict when trying to mix XML documents from different XML applications. This XML carries
HTML table An HTML element is a type of HTML (HyperText Markup Language) document component, one of several types of HTML nodes (there are also text nodes, comment nodes and others). The first used version of HTML was written by Tim Berners-Lee in 1993 ...
information:
Apples Oranges
This XML carries information about a
table Table may refer to: * Table (furniture), a piece of furniture with a flat surface and one or more legs * Table (landform), a flat area of land * Table (information), a data arrangement with rows and columns * Table (database), how the table data ...
(i.e. a piece of furniture): African Coffee Table80120
If these XML fragments were added together, there would be a name conflict. Both contain a element, but the elements have different content and meaning. An XML parser will not know how to handle these differences.


Solution via prefix

Name conflicts in XML can easily be avoided using a name prefix. The following XML distinguishes between information about the HTML table and furniture by prefixing "h" and "f" at the beginning of the elements. Apples Oranges African Coffee Table 80 120


Naming system

A name in a namespace consists of a namespace name and a local name. The namespace name is usually applied as a prefix to the local name. In
augmented Backus–Naur form In computer science, augmented Backus–Naur form (ABNF) is a metalanguage based on Backus–Naur form (BNF), but consisting of its own syntax and derivation rules. The motive principle for ABNF is to describe a formal system of a language to be use ...
: name = <namespace name> separator <local name> When local names are used by themselves, name resolution is used to decide which (if any) particular name is alluded to by some particular local name.


Examples


Delegation

Delegation of responsibilities between parties is important in real-world applications, such as the structure of the World Wide Web. Namespaces allow delegation of identifier assignment to multiple name issuing organisations whilst retaining global uniqueness. A central
Registration authority Registration authorities exist for many standards organizations, such as ANNA (Association of National Numbering Agencies for ISIN), the Object Management Group, W3C, IEEE and others. In general, registration authorities all perform a similar fun ...
registers the assigned namespace names allocated. Each namespace name is allocated to an organisation which is subsequently responsible for the assignment of names in their allocated namespace. This organisation may be a name issuing organisation that assign the names themselves, or another
Registration authority Registration authorities exist for many standards organizations, such as ANNA (Association of National Numbering Agencies for ISIN), the Object Management Group, W3C, IEEE and others. In general, registration authorities all perform a similar fun ...
which further delegates parts of their namespace to different organisations.


Hierarchy

A naming scheme that allows subdelegation of namespaces to third parties is a hierarchical namespace. A hierarchy is recursive if the syntax for the namespace names is the same for each subdelegation. An example of a recursive hierarchy is the
Domain name system The Domain Name System (DNS) is a hierarchical and distributed naming system for computers, services, and other resources in the Internet or other Internet Protocol (IP) networks. It associates various information with domain names assigned t ...
. An example of a non-recursive hierarchy are
Uniform Resource Name A Uniform Resource Name (URN) is a Uniform Resource Identifier (URI) that uses the scheme. URNs are globally unique persistent identifiers assigned within defined namespaces so they will be available for a long period of time, even after the res ...
representing an
Internet Assigned Numbers Authority The Internet Assigned Numbers Authority (IANA) is a standards organization that oversees global IP address allocation, autonomous system number allocation, root zone management in the Domain Name System (DNS), media types, and other Inte ...
(IANA) number.


Namespace versus scope

A namespace name may provide context (
scope Scope or scopes may refer to: People with the surname * Jamie Scope (born 1986), English footballer * John T. Scopes (1900–1970), central figure in the Scopes Trial regarding the teaching of evolution Arts, media, and entertainment * Cinem ...
in computer science) to a name, and the terms are sometimes used interchangeably. However, the context of a name may also be provided by other factors, such as the location where it occurs or the syntax of the name.


In programming languages

For many programming languages, namespace is a context for their
identifiers An identifier is a name that identifies (that is, labels the identity of) either a unique object or a unique ''class'' of objects, where the "object" or class may be an idea, physical countable object (or class thereof), or physical noncountable ...
. In an operating system, an example of namespace is a directory. Each name in a directory uniquely identifies one file or subdirectory. As a rule, names in a namespace cannot have more than one meaning; that is, different meanings cannot share the same name in the same namespace. A namespace is also called a
context Context may refer to: * Context (language use), the relevant constraints of the communicative situation that influence language use, language variation, and discourse summary Computing * Context (computing), the virtual environment required to su ...
, because the same name in different namespaces can have different meanings, each one appropriate for its namespace. Following are other characteristics of namespaces: * Names in the namespace can represent objects as well as
concept Concepts are defined as abstract ideas. They are understood to be the fundamental building blocks of the concept behind principles, thoughts and beliefs. They play an important role in all aspects of cognition. As such, concepts are studied by ...
s, be the namespace a natural or ethnic language, a
constructed language A constructed language (sometimes called a conlang) is a language whose phonology, grammar, and vocabulary, instead of having developed naturally, are consciously devised for some purpose, which may include being devised for a work of fiction ...
, the
technical terminology Jargon is the specialized terminology associated with a particular field or area of activity. Jargon is normally employed in a particular communicative context and may not be well understood outside that context. The context is usually a partic ...
of a profession, a
dialect The term dialect (from Latin , , from the Ancient Greek word , 'discourse', from , 'through' and , 'I speak') can refer to either of two distinctly different types of linguistic phenomena: One usage refers to a variety of a language that is a ...
, a
sociolect In sociolinguistics, a sociolect is a form of language ( non-standard dialect, restricted register) or a set of lexical items used by a socioeconomic class, profession, an age group, or other social group. Sociolects involve both passive acqui ...
, or an artificial language (e.g., a
programming language A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language. The description of a programming ...
). * In the
Java programming language Java is a high-level, class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible. It is a general-purpose programming language intended to let programmers ''write once, run anywh ...
, identifiers that appear in namespaces have a short (local) name and a unique long "qualified" name for use outside the namespace. * Some compilers (for languages such as
C++ C++ (pronounced "C plus plus") is a high-level general-purpose programming language created by Danish computer scientist Bjarne Stroustrup as an extension of the C programming language, or "C with Classes". The language has expanded significan ...
) combine namespaces and names for internal use in the compiler in a process called ''
name mangling In compiler construction, name mangling (also called name decoration) is a technique used to solve various problems caused by the need to resolve unique names for programming entities in many modern programming languages. It provides a way of e ...
''. As well as its abstract language technical usage as described above, some languages have a specific keyword used for explicit namespace control, amongst other uses. Below is an example of a namespace in C++: #include // This is how one brings a name into the current scope. In this case, it's // bringing them into global scope. using std::cout; using std::endl; namespace box1 namespace box2 int main()


Computer-science considerations

A namespace in computer science (sometimes also called a name scope) is an abstract container or environment created to hold a logical grouping of unique identifiers or symbols (i.e. names). An identifier defined in a namespace is associated only with that namespace. The same identifier can be independently defined in multiple namespaces. That is, an identifier defined in one namespace may or may not have the same meaning as the same identifier defined in another namespace. Languages that support namespaces specify the rules that determine to which namespace an identifier (not its definition) belongs. This concept can be illustrated with an analogy. Imagine that two companies, X and Y, each assign ID numbers to their employees. X should not have two employees with the same ID number, and likewise for Y; but it is not a problem for the same ID number to be used at both companies. For example, if Bill works for company X and Jane works for company Y, then it is not a problem for each of them to be employee #123. In this analogy, the ID number is the identifier, and the company serves as the namespace. It does not cause problems for the same identifier to identify a different person in each namespace. In large
computer program A computer program is a sequence or set of instructions in a programming language for a computer to execute. Computer programs are one component of software, which also includes documentation and other intangible components. A computer program ...
s or documents it is common to have hundreds or thousands of identifiers. Namespaces (or a similar technique, see Emulating namespaces) provide a mechanism for hiding local identifiers. They provide a means of grouping logically related identifiers into corresponding namespaces, thereby making the system more
modular Broadly speaking, modularity is the degree to which a system's components may be separated and recombined, often with the benefit of flexibility and variety in use. The concept of modularity is used primarily to reduce complexity by breaking a s ...
. Data storage devices and many modern
programming language A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language. The description of a programming ...
s support namespaces. Storage devices use directories (or folders) as namespaces. This allows two files with the same name to be stored on the device so long as they are stored in different directories. In some programming languages (e.g.
C++ C++ (pronounced "C plus plus") is a high-level general-purpose programming language created by Danish computer scientist Bjarne Stroustrup as an extension of the C programming language, or "C with Classes". The language has expanded significan ...
,
Python Python may refer to: Snakes * Pythonidae, a family of nonvenomous snakes found in Africa, Asia, and Australia ** ''Python'' (genus), a genus of Pythonidae found in Africa and Asia * Python (mythology), a mythical serpent Computing * Python (pro ...
), the identifiers naming namespaces are themselves associated with an enclosing namespace. Thus, in these languages namespaces can nest, forming a namespace
tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
. At the root of this tree is the unnamed global namespace.


Use in common languages


=C

= It is possible to use anonymous structs as namespaces in C since
C99 C99 (previously known as C9X) is an informal name for ISO/IEC 9899:1999, a past version of the C programming language standard. It extends the previous version ( C90) with new features for the language and the standard library, and helps impl ...
. // helper.c static int _add(int a, int b) const struct helper = ; // helper.h const struct helper; // main.c #include #include "helper.h" int main()


=C++

= In
C++ C++ (pronounced "C plus plus") is a high-level general-purpose programming language created by Danish computer scientist Bjarne Stroustrup as an extension of the C programming language, or "C with Classes". The language has expanded significan ...
, a namespace is defined with a namespace block. namespace abc Within this block, identifiers can be used exactly as they are declared. Outside of this block, the namespace specifier must be prefixed. For example, outside of namespace abc, bar must be written abc::bar to be accessed. C++ includes another construct that makes this verbosity unnecessary. By adding the line using namespace abc; to a piece of code, the prefix abc:: is no longer needed. Identifiers that are not explicitly declared within a namespace are considered to be in the global namespace. int foo; These identifiers can be used exactly as they are declared, or, since the global namespace is unnamed, the namespace specifier :: can be prefixed. For example, foo can also be written ::foo. Namespace resolution in C++ is hierarchical. This means that within the hypothetical namespace food::soup, the identifier chicken refers to food::soup::chicken. If food::soup::chicken doesn't exist, it then refers to food::chicken. If neither food::soup::chicken nor food::chicken exist, chicken refers to ::chicken, an identifier in the global namespace. Namespaces in C++ are most often used to avoid
naming collision A naming collision is a circumstance where two or more identifiers in a given namespace or a given scope cannot be unambiguously resolved, and such unambiguous resolution is a requirement of the underlying system. Example: XML element names I ...
s. Although namespaces are used extensively in recent C++ code, most older code does not use this facility because it did not exist in early versions of the language. For example, the entire
C++ Standard Library The C standard library or libc is the standard library for the C programming language, as specified in the ISO C standard. ISO/IEC (2018). '' ISO/IEC 9899:2018(E): Programming Languages - C §7'' Starting from the original ANSI C standard, it was ...
is defined within namespace std, but before standardization many components were originally in the global namespace. A programmer can insert the using directive to bypass namespace resolution requirements and obtain backwards compatibility with older code that expects all identifiers to be in the global namespace. However the use of the using directive for reasons other than backwards compatibility (e.g., convenience) is considered to be against good code practices.


=Java

= In
Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mos ...
, the idea of a namespace is embodied in
Java package A Java package organizes Java classes into namespaces, providing a unique namespace for each type it contains. Classes in the same package can access each other's package-private and protected members. In general, a package can contain the follo ...
s. All code belongs to a package, although that package need not be explicitly named. Code from other packages is accessed by prefixing the package name before the appropriate identifier, for example class String in package
java.lang Java Platform, Standard Edition (Java SE) is a computing platform for development and deployment of portable code for desktop and server environments. Java SE was formerly known as Java 2 Platform, Standard Edition (J2SE). The platform uses ...
can be referred to as java.lang.String (this is known as the fully qualified class name). Like C++, Java offers a construct that makes it unnecessary to type the package name (import). However, certain features (such as
reflection Reflection or reflexion may refer to: Science and technology * Reflection (physics), a common wave phenomenon ** Specular reflection, reflection from a smooth surface *** Mirror image, a reflection in a mirror or in water ** Signal reflection, in ...
) require the programmer to use the fully qualified name. Unlike C++, namespaces in Java are not hierarchical as far as the syntax of the language is concerned. However, packages are named in a hierarchical manner. For example, all packages beginning with java are a part of the
Java platform Java is a set of computer software and specifications developed by James Gosling at Sun Microsystems, which was later acquired by the Oracle Corporation, that provides a system for developing application software and deploying it in a cro ...
—the package contains classes core to the language, and contains core classes specifically relating to reflection. In Java (and
Ada Ada may refer to: Places Africa * Ada Foah, a town in Ghana * Ada (Ghana parliament constituency) * Ada, Osun, a town in Nigeria Asia * Ada, Urmia, a village in West Azerbaijan Province, Iran * Ada, Karaman, a village in Karaman Province, ...
, C#, and others), namespaces/packages express semantic categories of code. For example, in C#, namespace System contains code provided by the system (the
.NET Framework The .NET Framework (pronounced as "''dot net"'') is a proprietary software framework developed by Microsoft that runs primarily on Microsoft Windows. It was the predominant implementation of the Common Language Infrastructure (CLI) until bein ...
). How specific these categories are and how deep the hierarchies go differ from language to language.
Function Function or functionality may refer to: Computing * Function key, a type of key on computer keyboards * Function model, a structured representation of processes in a system * Function object or functor or functionoid, a concept of object-oriente ...
and
class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differentl ...
scope Scope or scopes may refer to: People with the surname * Jamie Scope (born 1986), English footballer * John T. Scopes (1900–1970), central figure in the Scopes Trial regarding the teaching of evolution Arts, media, and entertainment * Cinem ...
s can be viewed as implicit namespaces that are inextricably linked with visibility, accessibility, and object lifetime.


=C#

= Namespaces are heavily used in C# language. All .NET Framework classes are organized in namespaces, to be used more clearly and to avoid chaos. Furthermore, custom namespaces are extensively used by programmers, both to organize their work and to avoid
naming collision A naming collision is a circumstance where two or more identifiers in a given namespace or a given scope cannot be unambiguously resolved, and such unambiguous resolution is a requirement of the underlying system. Example: XML element names I ...
s. When referencing a class, one should specify either its fully qualified name, which means namespace followed by the class name, System.Console.WriteLine("Hello World!"); int i = System.Convert.ToInt32("123"); or add a using statement. This, eliminates the need to mention the complete name of all classes in that namespace. using System; Console.WriteLine("Hello World!"); int i = Convert.ToInt32("123"); In the above examples, System is a namespace, and Console and Convert are classes defined within System.


=Python

= In
Python Python may refer to: Snakes * Pythonidae, a family of nonvenomous snakes found in Africa, Asia, and Australia ** ''Python'' (genus), a genus of Pythonidae found in Africa and Asia * Python (mythology), a mythical serpent Computing * Python (pro ...
, namespaces are defined by the individual modules, and since modules can be contained in hierarchical packages, then namespaces are hierarchical too. In general when a module is imported then the names defined in the module are defined via that module's namespace, and are accessed in from the calling modules by using the fully qualified name. # assume modulea defines two functions : func1() and func2() and one class : Class1 import Modulea Modulea.func1() Modulea.func2() a = Modulea.Class1() The from ... import ... statement can be used to insert the relevant names directly into the calling module's namespace, and those names can be accessed from the calling module without the qualified name: # assume Modulea defines two functions : func1() and func2() and one class : Class1 from Modulea import func1 func1() func2() # this will fail as an undefined name, as will the full name Modulea.func2() a = Class1() # this will fail as an undefined name, as will the full name Modulea.Class1() Since this directly imports names (without qualification) it can overwrite existing names with no warnings. A special form of the statement is from ... import * which imports all names defined in the named package directly in the calling module's namespace. Use of this form of import, although supported within the language, is generally discouraged as it pollutes the namespace of the calling module and will cause already defined names to be overwritten in the case of name clashes. Python also supports import x as y as a way of providing an alias or alternative name for use by the calling module: import numpy as np a = np.arange(1000)


= XML namespace

= In
XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable ...
, the XML namespace specification enables the names of elements and attributes in an XML document to be unique, similar to the role of namespaces in programming languages. Using XML namespaces, XML documents may contain element or attribute names from more than one XML vocabulary.


= PHP

= Namespaces were introduced into
PHP PHP is a general-purpose scripting language geared toward web development. It was originally created by Danish-Canadian programmer Rasmus Lerdorf in 1993 and released in 1995. The PHP reference implementation is now produced by The PHP Group. ...
from version 5.3 onwards. Naming collision of classes, functions and variables can be avoided. In
PHP PHP is a general-purpose scripting language geared toward web development. It was originally created by Danish-Canadian programmer Rasmus Lerdorf in 1993 and released in 1995. The PHP reference implementation is now produced by The PHP Group. ...
, a namespace is defined with a namespace block. # File phpstar/foobar.php namespace phpstar; class FooBar We can reference a PHP namespace with the following different ways: # File index.php # Include the file include "phpstar/foobar.php"; # Option 1: directly prefix the class name with the namespace $obj_foobar = new \phpstar\FooBar(); # Option 2: import the namespace use phpstar\FooBar; $obj_foobar = new FooBar(); # Option 2a: import & alias the namespace use phpstar\FooBar as FB; $obj_foobar = new FB(); # Access the properties and methods with regular way $obj_foobar->foo(); $obj_foobar->bar();


Emulating namespaces

In programming languages lacking language support for namespaces, namespaces can be emulated to some extent by using an
identifier naming convention In computer programming, a naming convention is a set of rules for choosing the character sequence to be used for identifiers which denote variables, types, functions, and other entities in source code and documentation. Reasons for using a na ...
. For example, C libraries such as
libpng libpng is the official Portable Network Graphics (PNG) reference library (originally called pnglib). It is a platform-independent library that contains C functions for handling PNG images. It supports almost all of PNG's features, is extensible ...
often use a fixed prefix for all functions and variables that are part of their exposed interface. Libpng exposes identifiers such as: png_create_write_struct png_get_signature png_read_row png_set_invalid This
naming convention A naming convention is a convention (generally agreed scheme) for naming things. Conventions differ in their intents, which may include to: * Allow useful information to be deduced from the names based on regularities. For instance, in Manhatta ...
provides reasonable assurance that the identifiers are unique and can therefore be used in larger programs without
naming collision A naming collision is a circumstance where two or more identifiers in a given namespace or a given scope cannot be unambiguously resolved, and such unambiguous resolution is a requirement of the underlying system. Example: XML element names I ...
s. Likewise, many packages originally written in Fortran (e.g.,
BLAS Basic Linear Algebra Subprograms (BLAS) is a specification that prescribes a set of low-level routines for performing common linear algebra operations such as vector addition, scalar multiplication, dot products, linear combinations, and matrix ...
,
LAPACK LAPACK ("Linear Algebra Package") is a standard software library for numerical linear algebra. It provides routines for solving systems of linear equations and linear least squares, eigenvalue problems, and singular value decomposition. It als ...
) reserve the first few letters of a function's name to indicate which group it belongs to. This technique has several drawbacks: * It doesn't scale well to nested namespaces; identifiers become excessively long since all uses of the identifiers must be fully namespace-qualified. * Individuals or organizations may use inconsistent naming conventions, potentially introducing unwanted obfuscation. * Compound or "query-based" operations on groups of identifiers, based on the namespaces in which they are declared, are rendered unwieldy or unfeasible. * In languages with restricted identifier length, the use of prefixes limits the number of characters that can be used to identify what the function does. This is a particular problem for packages originally written in FORTRAN 77, which offered only 6 characters per identifier. For example, the name of the
BLAS Basic Linear Algebra Subprograms (BLAS) is a specification that prescribes a set of low-level routines for performing common linear algebra operations such as vector addition, scalar multiplication, dot products, linear combinations, and matrix ...
function DGEMM function indicates that it operates on double-precision numbers ("D") and general matrices ("GE"), and only the last two characters show what it actually does: matrix-matrix multiplication (the "MM"). There are several advantages: * No special software tools are required to locate names in source-code files. A simple program like
grep grep is a command-line utility for searching plain-text data sets for lines that match a regular expression. Its name comes from the ed command ''g/re/p'' (''globally search for a regular expression and print matching lines''), which has the sa ...
suffices. * There are no namespace name conflicts. * There is no need for name-mangling, and thus no potential incompatibility problems.


See also

* 11-digit
delivery point In a postal system, a delivery point (sometimes DP) is a single mailbox or other place at which mail is delivered. It differs from a street address, in that each address may have several delivery points, such as an apartment, office department, ...
ZIP code *
Binomial nomenclature In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
(genus-species in
biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary i ...
) * Chemical nomenclature *
Dewey Decimal Classification The Dewey Decimal Classification (DDC), colloquially known as the Dewey Decimal System, is a proprietary library classification system which allows new books to be added to a library in their appropriate location based on subject. Section 4.1 ...
*
Digital object identifier A digital object identifier (DOI) is a persistent identifier or handle used to uniquely identify various objects, standardized by the International Organization for Standardization (ISO). DOIs are an implementation of the Handle System; they a ...
*
Domain Name System The Domain Name System (DNS) is a hierarchical and distributed naming system for computers, services, and other resources in the Internet or other Internet Protocol (IP) networks. It associates various information with domain names assigned t ...
*
Identity (object-oriented programming) In object-oriented programming, object-oriented design and object-oriented analysis, the identity of an object is its being distinct from any other object, regardless of the values of the objects' properties. Having identity is a fundamental prope ...
*
Library of Congress Classification The Library of Congress Classification (LCC) is a system of library classification developed by the Library of Congress in the United States, which can be used for shelving books in a library. LCC is mainly used by large research and academic librar ...
* Star catalogues and astronomical naming conventions *
XML namespace XML namespaces are used for providing uniquely named elements and attributes in an XML document. They are defined in a W3C recommendation. An XML instance may contain element or attribute names from more than one XML vocabulary. If each vocabular ...
* Argument-dependent name lookup


References

{{DEFAULTSORT:Namespace Naming conventions